Thursday, April 25, 2013

New paper finds another non-hockey-stick in China

A paper published today in Palaeogeography, Palaeoclimatology, Palaeoecology reconstructs temperatures from 1834-2010 in southeastern China, and shows temperatures at the end of the record in 2010 were cooler than multiple other periods in the past including the 1930's, early part of the 1900's and during the 1800's.The paper, co-authored by Climategate participant Ed Cook, attempts to claim the rate of temperature rise from 1948-2010 is unprecedented, but it is obvious from examination of the data presented in Figure 5 that the temperature rise rate and amount from ~1910-1935 was both faster and greater than from 1948-2010 [2nd graph below]. Furthermore, it is obvious that the peak reached at the end of the 20th century is related to the record 1997-1998 El Nino natural ocean oscillation, and that temperatures have cooled since.

Fig. 5. January-July minimum temperature reconstruction in the Dabie Mountains, southeastern China. (a), comparison of actual and reconstructed temperatures for 1956 to 2010; and (b), the reconstructed temperature from 1834 to 2010.

The recent warming and temperature increase rate are unprecedented [not].

Abstract

Previous tree-ring studies indicate that tree growth at high elevations is strongly limited by temperatures in the southeastern China, where the climate is dominated by the East Asian monsoon. Based on this result, we built a highly replicated 202-year tree-ring width chronology from high elevation sites in the Dabie Mountains, southeastern China. The most reliable period of the chronology is from 1834 to 2011 according to a subsample signal strength cutoff of 0.85. Based on this chronology, January-July minimum temperature was reconstructed for the last 178 years, with an explained variance of 57.6% during the instrumental period 1956–2010. The reconstructed temperature series matches reasonably well with three other tree-ring based temperature reconstructions at decadal time scales in the region. The coldest periods are 1891–1898 and 1904–1914, however, the longest cold period is from 1948 to 1973. The warmest period is 1990–2010. Both the recent (1990–2010) warming and recent (1948–2010) temperature increase rate are unprecedented [not] during the past 178 years in the study region.